Pressure Reducing Valve for steam RP 45

Transcription

1 Pressure Reducing Valve for steam RP 45 DESCRIPTION The RP45 series pressure reducing valves are single seat bellows sealed controllers, operating without auxiliary energy,designed for use on steam, compressed air, industrial insert gases and liquids compatible with the construction. They are particularly suitable for reducing steam pressure in all energy and process systems where pressures should be kept constant. OPERATION Pressure reduction is achieved by means of variable throttling of the inlet flow at the valve seat by variation of the flow area between seat and disc. The outlet pressure which is transmitted through the feed-back line to the diaphragm chamber counteracts the spring force acting on the valve spindle and controls the valve aperture corresponding to the spring setting and thus to the required outlet pressure. MAIN FEATURES Specially designed high durability bellows, providing pressure balancing and friction less plug stem. Robust construction (fit-and-forget). Suitable for use with high pressure turndowns. Interchangeable actuators OPTION: USE: AVAILABLE MODELS: Soft sealing for steam Nitrile rubber soft seated version for air and gas applications where tight shut-off is required. Low-noise flow divider Steam, compressed air and other gases and liquids complete with the construction. RP45G and RP45GT or N-PN16 cast iron RP45S and RP45ST or N-PN40 cast steel RP45I and RP45IT or N-Stainless steel (All wetted parts free of non-ferrous metal or in St.Steel.). Suffix T : Soft seated with PTFE/GR Suffix N : soft seated with nitrile rubber SIZES: DN 15 to DN 100 CONNECTIONS: RP45G Flanged EN PN16 RP45S or I Flanged EN PN40 INSTALLATION: Horizontal installation. An Y strainer, steam separator and steam trap should be provided upstream the valve. See IMI, installation and maintenance instructions.

2 LIMITING CONDITIONS RP45G RP45S RP45I RP45GT RP45ST RP45IT RP45GN* RP45SN * RP45IN * Body design conditions PN16 PN40 PN40 PN16 PN40 PN40 PN16 PN40 PN40 Max.upstream pressure 13 bar 25 bar 25 bar 13 bar 25 bar 25 bar 13 bar 25 bar 25 bar Max.downstream pressure ** 13 bar 13 bar 13 bar 13 bar 13 bar 13 bar 13 bar 13 bar 13 bar Min.downstream pressure 0,15 bar 0,15 bar 0,15 bar 0,15 bar 0,15 bar 0,15 bar 0,15 bar 0,15 bar 0,15 bar Max.operating temperature 200ºC 250ºC 250ºC 200 ºC 220 ºC 220 ºC 90 ºC 90 ºC 90 ºC Max.reducing ratio 25:1 25:1 25:1 25:1 25:1 25:1 10:1 10:1 10:1 Rangeability 10:1 10:1 10:1 10:1 10:1 10:1 10:1 10:1 10:1 Max.cold hydraulic test 24 bar 25 bar 25 bar 24 bar 25 bar 25 bar 24 bar 25 bar 25 bar Max.hyd. factory valve body test 24 bar 60 bar 60 bar 24 bar 60 bar 60 bar 24 bar 60 bar 60 bar *Suffix N : - a maximum turndown ratio 10:1 should be observed. Other soft materials on request. ** Others on request with bellows or piston actuator SIZE DN DIMENSIONS (mm) VALVE ACTUATOR WGT. A B TYPE Kgs ,7 A , ,7 A , ,7 A , ,7 A , ,7 A , ,7 A , , , ,7 C WGT. Kgs MATERIALS POS. DESIGNATION MATERIAL 1 Valve body (PN16) GJL-250 / Valve body (PN40) GP240GH / Valve body (PN40) CF8M / Piston body GJS / Valve seat HARDENED ST.STEEL 4 * Valve disc HARDENED ST.STEEL 4 * Soft valve disc AISI304/ ;NBR (PTFE/GR,etc) 5 Guide AISI 304 / * Bellows AISI 316 Ti / * Diaphragm chamber GJL-250 / Spindle AISI 304 / Regulating spring SPRING STEEL 10 * Impulse line COPPER 11 * Condensate vessel a) S235JRG2 / * Available spare parts. a) Not necessary when in operation with low temperature compressed air or water.

3 SATURATED STEAM CAPACITY TABLE (Kg/h) ( P2 < 0,58 P1 ) INLET barg VALVE SIZE DN15 DN20 DN25 DN32 DN40 DN50 DN65 DN80 DN100 0, , , , ACTUATOR AND SPRING SELECTION TABLE VALVE SIZE DN Kvs m3/h ACTUATOR A - 4 A - 4 A - 3 A - 2 A - 21 A - 1 A ,8 20 6,9 25 9, , , , , , ,5 Outlet (bar) 0,15-0,49 0,5-0,99 1,0-1,9 2-4,2 4,3-6,9 7-8,5 8,6-13 Spring Nº Outlet (bar) 0,15-0,49 0,5-0,99 1,0-1,9 2-4,2 4,3-6,9 7-8,5 8,6-13 Spring Nº Outlet (bar) 0,15-0,45 0,46-0,99 1,0-1, ,1-8, / Spring Nº / Outlet (bar) 0,15-0,45 0,46-0,99 1,0-1,9 2-6,0 6,1-13 / / Spring Nº / /

4 Correction factors: The given capacities apply to the pressure reducing valves at critical pressure drop (downstream pressure in barg about 58% of the upstream pressure barg or lower). In case of non-critical pressure drop a correction factor must be used as follows: PRESSURE RATIO * P2 / P1 CORRECTION FACTOR f 0,7 1,25 0,8 1,6 No correction factor should be used for smaller pressure ratios than ,9 2,25 Superheated steam: * Pressure ratio in bar abs (barg + 1) If superheated steam is to be reduced instead of saturated steam a correction factor has to be applied as well, the required mass flow must be multiplied by the following factor : Vh_, where Vh = specific volume of superheated steam and Vs = specific volume of saturated steam. Vs HOW TO SIZE ( using table for steam ) Example (valve selection) : Saturated steam capacity: 300Kg/h; Upstream pressure: 3 bar; Downstream pressure required: 2bar. Solution: First determine correction factor for pressure ratio: = 0.75 f = 1. 25, Then multiply the given capacity: = 375Kg h Go to 3 bar in the column bar of the capacity table. By following the horizontal line you can find out the values for selection of pressure reducing valve. Looking for an equal or higher value than 375 Kg/h. In this case it will be 400 Kg/h. Now, go to the top of the table and read off the nominal size: DN32 On the actuator and spring selection table, for downstream pressure of 2 bar we may see that the recommended actuator is type A-2, considering the valve supplied with spring Nr.60. How to order: RP45G DN32 PN16 valve complete with spring Nr.60, type A-2 actuator, condensate vessel and copper tube impulse line. HOW TO SIZE ( using Kvs) : please consult formulas on IS PV10.00 E or consult factory. INSTALLATION RECOMMENDATIONS RP45 is designed primarily for steam, compressed air and non inflammable gases. It has limited use for neutral liquids since the plug close in the same direction of the fluid flow, which can produce vibrations and water hammer when used at less than 20% of capacity. To avoid this, valve can be installed with the fluid direction against the plug under certain conditions. Please consult the factory. At service conditions where the temperature is more than 100ºC it is necessary to protect the diaphragm against overheating by using a seal pot. Never size the valve according to the pipe diameter in which it has to be fitted but according to the required actual flow.pipe sizing must also respect the maximum recommended flow velocities according to the medium. INSTALLATION Service conditions less than 100ºC : with gases the valve is ready to work. In case of liquids the actuator must be filled completely with liquid, so, the vent screw (12) should be open till the water flow without bubbles. The valve can be installed with the diaphragm pointing upwards or downwards. Service conditions more than 100ºC : Fill the seal pot (11) using a funnel (14) until the water emerges from the actuator vent (12 ) without bubbles.close the actuator vent screw (12 ) and proceed filling the pot until the water reaches the top and close it with the plug. The valve is now ready to work. The valve must be installed with the diaphragm pointing downwards. Downstream pressure should be adjusted with the key (13). Compressing the spring, spring force increase and downstream pressure increase. Relaxing the spring, spring force decrease and downstream pressure decrease. The valve closes when the downstream pressure rises.

5 Typical Installation MATERIALS POS. DESIGNATION MODEL 1 Pressure reducing valve RP45 1A Water seal pot POP 2 Humidity separator S 25 3 Steam trap FLT series 4 Sigh glass SW 12 5 Y Strainer IS 16 6 Y Strainer IS16F 7 Stop valve GV32B 8 Check valve RT 9 Stop valve VF16 9A Stop valve VF16 10 Safety valve - 11 Coil GSC Gauge cock GC Upsteam pressure gauge MAN Downstream pressure gauge MAN-100 Remarks : By-pass : if overpressure can not be accepted the use of by-pass is not recommended. In alternative, for critical process, two pressure reducing stations should be installed in parallel. PN ratings and materials according to the operating pressures. * The balance pipe connection is recommended to enter downstream pipe at a minimum of 1 meter from valve. Installation instructions are available (IMI-RP45) and typical assembling drawing. Special assembling designs may be produced on request.